Transcriptional Regulation by Angiotensin II in Vascular Smooth Muscle Cells

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Project Summary Atherosclerotic and hypertensive cardiovascular diseases (CVDs) are major causes of morbidity and mortality and a severe strain on our healthcare system. The peptide hormone Angiotensin II (Ang II) plays a major role in these pathologies due to its vasoconstrictive, pro-oxidant, -growth and -inflammatory properties in target cells such as vascular smooth muscle cells (VSMC). Several studies have documented the biochemical and signaling mechanisms of Ang II actions via the type 1 receptor (AT1R) in VSMC. However, the precise nuclear epigenetic mechanisms involved in AngII induced transcriptional regulation of pathological genes are not clear. It is increasingly recognized that profound alterations in chromatin structure, including changes in epigenetic posttranslational modifications (PTMs) of histones, such as Histone H3 -lysine methylation (H3Kme) can regulate the "active" or "inactive" state of genes. Recent evidence has also demonstrated the key roles of microRNAs (miRs) in gene regulation by posttranscriptional mechanisms. Our goal is to evaluate such epigenetic and miR mechanisms in Ang II actions in order to unravel new therapeutic targets. We hypothesize that the dysregulation of histone H3Kme and aberrant expression of key miRs contribute to Ang II induced VSMC dysfunction associated with various CVDs. This will be tested via 3 Specific Aims using state-of-the-art genome-wide profiling and bioinformatics approaches in cell culture along with relevant mouse models. Specific Aim 1 is to perform epigenome profiling of key chromatin histone H3Kme marks in VSMC treated with and without Ang II, evaluate the chromatin enzymes regulating these marks, and then their functional roles in VSMC. Specific Aim 2 is to profile the miR signatures in VSMC in response to Ang II and then determine the functional relevance of key differentially expressed miRs. Specific Aim 3 is to evaluate specific mouse models of increased Ang II action in order to determine the in vivo relevance of the epigenetic marks and miRs uncovered in Aims 1 and 2. When completed, the proposed work will yield novel new data describing the epigenetic and miR profiles of VSMC under Ang II treated conditions, and also bring in new next generation genome sequencing technologies to the field of vascular biology. The results can increase our understanding of Ang II actions, and identify new targets that might be developed as clinical therapies for CVDs such as hypertension and atherosclerosis.